A209953 Number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock having one, three or four distinct clockwise edge differences.

71, 567, 4521, 36057, 287559, 2293335, 18289737, 145863801, 1163288871, 9277428663, 73989087849, 590075690265, 4705955031303, 37530800068887, 299314580024457, 2387085211367865, 19037414768987367, 151826654264588919

Offset

1,1

Comments

Column 1 of A209960.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 6*a(n-1) + 15*a(n-2) + 6*a(n-3).

Empirical g.f.: x*(71 + 141*x + 54*x^2) / (1 - 6*x - 15*x^2 - 6*x^3). - Colin Barker, Jul 14 2018

Example

Some solutions for n=4:
..1..1....0..2....0..1....2..1....2..1....2..1....1..2....1..2....1..2....2..1
..0..0....2..1....2..0....0..2....0..2....0..0....0..2....1..1....0..2....2..2
..2..0....0..1....1..2....1..1....2..1....1..1....2..1....1..1....0..2....1..2
..0..0....0..1....2..0....1..2....0..2....1..0....2..0....1..0....2..2....0..2
..0..0....1..1....0..1....1..1....1..0....2..2....0..1....1..2....0..2....2..2

Crossrefs

Cf. A209960.

Sequence in context: A250982 A250975 A209960 * A251390 A251383 A180327

Adjacent sequences: A209950 A209951 A209952 * A209954 A209955 A209956

Keyword

nonn

Author

R. H. Hardin, Mar 16 2012

Status

approved